chemical changes and electrolysis

Question 1

Gain of oxygen is (a) and the loss of oxygen is (b)

Answer 1

(a) oxidation
(b) reduction

Question 2

Is the more reactive a metal is, the more easily it loses electrons?

Answer 2

Yes

Question 3

What do metals that react with water give?

Answer 3

Metal hydroxide and hydrogen gas.

Question 4

What do metals that react with a dilute acid give?

Answer 4

Metal salts and hydrogen gas.

Question 5

More reactive metals will displace (a) reactive metals from solutions of metal (b)

Answer 5

(a) less
(b) salts

Question 6

What is the phonetic method of remembering the reactive series?

Answer 6

PoSLiCaMZIC.

Question 7

Where are metals from the Earth’s crust found?

Answer 7

In rocks called ores, they contain enough metal to make it worthwhile to use them.

Question 8

These metals can be extracted using electrolysis because they are more reactive than carbon and their oxides are not reduced by heating with carbon.

Answer 8

Potassium, sodium, lithium, calcium, magnesium, aluminium.

Question 9

These 3 metals are less reactive than carbon and therefore their oxides can be reduced to the metal by heating with carbon.

Answer 9

Zinc, iron, copper.

Question 10

These metals are found uncombined and do not have to be extracted.

Answer 10

Gold and silver.

Question 11

What is the reason acids have similar properties?

Answer 11

They all contain hydrogen and when in aqueous solution they all give hydrogen ions.

Question 12

What acids react with metals to form salts and hydrogen?

Answer 12

Hydrochloric and sulfuric.

Question 13

(a) are soluble metal hydroxides; bases are (b) metal oxides and hydroxides.

Answer 13

(a) Alkalis
_(b)_insoluble

Question 14

acid + carbonate -> (a) + (b) + (c)

Answer 14

(a) salt
(b) water
(c) carbon dioxide

Question 15

When is an aqueous solution formed?

Answer 15

When a substance dissolves in water.

Question 16

In neutralisation, H+ and OH- react to give what?

Answer 16

Water.

Question 17

A concentrated solution of an acid has a
(a) amount (in moles) of the acid dissolved in the same (b) of water than a (c) solution.

Answer 17

(a) greater
(b) volume
(c) dilute

Question 18

A strong acid like hydrochloric acid is completely/partially ionised in aqueous solution. A weak acid like ethanoic acid is completely/partially ionised in aqueous solution.

Answer 18

completely
partially

Question 19

True or false: Strong is the same as concentrated and weak is the same as dilute.

Answer 19

False.

Question 20

What happens to the H+ ions if the pH value of a solution decreases by 1 unit.

Answer 20

They increase by 10 times or 1 order of magnitude.

Question 21

Electrolysis is the (a) up of an ionic compound using (b). It takes place when the ionic compounds are in (c) state or in aqueous solution because the ions are (d) to move around.

Answer 21

(a) splitting
(b) electricity
(c) liquid
(d) free

Question 22

What is the liquid decomposed by electrolysis called?

Answer 22

Electrolyte.

Question 23

When ions lose or (a) electrons at the electrodes they are (b).

Answer 23

(a) gain
(b) discharged

Question 24

Where do the negative ions move toward?

Answer 24

The positive electrode (anode) they lose electrons to form non- metallic elements.

Question 25

Where do the positive ions move toward?

Answer 25

The negative electrode (cathode) they gain electrons to form metallic elements.

Question 26

What are the reactions generally at the cathode? (half equation)

Answer 26

Mn+ + ne- = M

Question 27

What are the reactions at the anode? (half equation)

Answer 27

2Xm- --> X2 + 2me-

Question 28

What is used to extract aluminium?

Answer 28

The electrolyte used is aluminium oxide.

Question 29

Aluminium has a _(a)_ MP so to save energy and lower the operating temperature, the aluminium oxide is _(b)_ in a compound called _(c)_. _(d)_ is used at both electrodes. Aluminium ions are _(e)_ at the _(f)_ to give molten aluminium metal which is run off. At the anode, _(g)_ ions are discharged to form _(h)_ gas. This oxygen gas then reacts with the carbon anode to form _(i)_. The carbon anode burns away and loses mass.

Answer 29

(a) high (b) dissolved (c) cryolite (d) carbon (e) discharged (f) cathode (g) oxide (h) oxygen (i) carbon dioxide

Question 30

What is produced when metal+oxygen react

Answer 30

metal oxides

Question 31

What is the displacement order

Answer 31

a metal can only displace another metal from a compound if it is located above it in the reactivity series

Question 32

What are spectator ions

Answer 32

unchanged in a reaction

Question 33

How does potassium react with cold water

Answer 33

hydrogen produced ignites instantly, then the metal also ignites setting off a lilac flame

Question 34

How does sodium react with cold water

Answer 34

fizzes rapidly, melts to form a ball which floats around surface

Question 35

How does lithium react with cold water

Answer 35

fizzes and floats

Question 36

What is a redox reaction

Answer 36

reaction with both reduction and oxidation

Question 37

acid +metal oxides-> ?

Answer 37

salt+ water

Question 38

acid + hydroxide -> ?

Answer 38

salt + water

Question 39

how can u measure pH

Answer 39

universal indicator, pH probe

Question 40

process by which carbon is used to extract metals from their oxides when the metal is less reactive than carbon

Answer 40

1. metals can be extracted by reacting with carbon 2. in reduction the metal oxide loses oxygen to form a pure metal 3. reduction with carbon normally involves heating metal oxide in the presence of the carbon (often coal) 4. carbon is used because it is cheap and abundant

Question 41

metals that react with dilute acids but not cold water

Answer 41

magnesium aluminium zinc iron lead

Question 42

metals that don’t react with dilute acids

Answer 42

platinum gold silver copper

Question 43

what does the metal lose in a reduction reaction and form

Answer 43

oxygen, a pure metal

Question 44

what metal does hydrochloride acid make

Answer 44

chloride

Question 45

what metal does nitric acid make

Answer 45

nitrate

Question 46

what metal does sulphuric acid make

Answer 46

sulphate

Question 47

moles=…?

Answer 47

concentration x volume

Question 48

in an aqueous solution, at the anode what is formed when halide ions are present

Answer 48

halogen

Question 49

in an aqueous solution, at the anode what is formed when halide ions are absent

Answer 49

oxygen

Question 50

in an aqueous solution, at the anode what is formed when halide ions are absent

Answer 50

oxygen

Question 51

in an aqueous solution, at the cathode what is formed when the metal is more reactive than

Answer 51

hydrogen

Question 52

in an aqueous solution, at the cathode what is formed when the metal is less reactive than hydrogen

Answer 52

metal